Steering device

ABSTRACT

A steering device includes: a steering shaft a column jacket that are telescopically adjustable in an axial direction; a lock plate provided with a plurality of holes and a plurality of partition portions arranged in the axial direction; and a tooth that advances to and retreats from the lock plate, and that is engaged with one of the holes of the lock plate. The steering shaft includes a first end to which a steering member is mounted and a second end. The partition portions are provided such that a height of a first end-side partition portion in a direction toward the tooth retreated from the lock plate is greater than that of a second end-side partition portion positioned on a second end side of the first end-side partition portion.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2014-060935 filed onMar. 24, 2014 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a steering device.

2. Description of Related Art

For example, in a steering column for an automobile described inPublished Japanese Translation of PCT application No, 2011-516323 (JP2011-516323 A), a steering shaft to which a steering wheel is mounted isrotatably supported by an adjustment unit supported by a support unit.When the adjustment unit is moved in an axial direction of the steeringshaft, it is possible to adjust the position of the steering wheel inthe axial direction.

The adjustment unit is disposed between a pair of side plates in thesupport unit. Each side plate is provided with a hole, and a clampingbolt is inserted into the hole. A lock member is attached to theclamping bolt, and an operation lever is coupled to the clamping bolt.To the adjustment unit, an opposite lock member formed with a largenumber of notches is coupled via a breakaway plate.

When the operation lever is operated and the clamping bolt is therebyrotated, a protrusion of the lock member is inserted into any of thenotches of the opposite lock member, and the position of the steeringwheel in the axial direction is locked. At the time of vehiclecollision, due to the breakage of the breakaway plate, energy exerted atthe time of vehicle collision is absorbed.

In the steering column described in JP-A-2011-516323, a half-lockedstate in which the protrusion of the lock member is not inserted intothe notch but is kept in pressure contact with a boundary portionbetween the adjacent notches in the opposite lock member can occur. Whenthe vehicle collision occurs in the half-locked state, depending on acollision speed, it takes time for the protrusion to be engaged with thenear notch before the breakaway plate is broken (before separation) sothat the timing of breakage of the breakaway plate is delayed. As aresult, there is a possibility that variations occur in characteristicsof energy absorption (what is called separation characteristics) at thetime of the vehicle collision in accordance with a distance of movementof the protrusion before the protrusion is engaged with the notch.

SUMMARY OF THE INVENTION

The invention provides the steering device capable of suppressingvariations in characteristics of energy absorption at the time of thevehicle collision.

An aspect of the invention is a steering device including: a steeringshaft including a first end to which a steering member is mounted and asecond end, wherein the steering shaft is telescopically adjustable inan axial direction of the steering shaft; a column jacket rotatablysupporting the steering shaft and including an upper jacket positionedon a first end side and a lower jacket positioned on a second end side,wherein the column jacket is telescopically adjustable together with thesteering shaft with movement of the upper jacket relative to the lowerjacket in the axial direction; a lock plate fixed to the upper jacketand provided with a plurality of holes arranged in the axial directionand a plurality of partition portions arranged in the axial direction,wherein each of the partition portions is adjacent to the first end sideof the corresponding one of the holes; a support bracket fixed to avehicle body and supporting the column jacket; an operation membersupported by the support bracket, wherein the operation member isoperated when the steering shaft and the column jacket aretelescopically adjusted; and a tooth that advances to and retreats fromthe lock plate in accordance with operation of the operation member, andthat advances to the lock plate to be engaged with one of the holes ofthe lock plate. In the steering device, the partition portions areprovided such that a height of a first end-side partition portion in adirection toward the tooth retreated from the lock plate is greater thanthat of a second end-side partition portion positioned on the second endside of the first end-side partition portion.

According to the above configuration, in the steering device, when thetooth is engaged with one of the holes in the lock plate fixed to theupper jacket by operating the operation member, it is possible to stopextension and contraction of the steering shaft and the column jacketand lock the position of the steering member in the axial direction. Onthe other hand, when the tooth retreats and is disengaged from the hole,it is possible to cause the steering shaft and the column jacket toextend or contract and adjust the position of the steering member in theaxial direction.

In the lock plate, one partition portion is provided for each of theholes, adjacent to the first end side of the hole.

When a vehicle collision occurs in a state in which the tooth is notengaged with any of the holes and comes in pressure contact with any ofthe partition portions, the lock plate moves to the second end sidetogether with the upper jacket. In the lock plate, the partitionportions arranged in the axial direction are provided such that a heightof a first end-side partition portion is greater than that of a secondend-side partition portion positioned on the second end side of thefirst end-side partition portion. Accordingly, with the movement of thelock plate, the tooth comes in contact with the next partition portion,which is higher than the partition portion with which the tooth has beenin pressure contact and is adjacent to the first end side of thepartition portion, is guided to the hole between the next partitionportion and the pressure-contacted partition portion by the nextpartition portion, and can be engaged with the hole.

That is, even when the vehicle collision has occurred in the state inwhich the tooth is in pressure contact with any partition portion, it ispossible to cause the tooth to be engaged with the hole adjacent to thefirst end side of the partition portion (referred to as the “next hole”)more reliably. With this, it is possible to make the movement distanceof the tooth from when the tooth is in pressure contact with thepartition portion to when the tooth is engaged with the next holesubstantially constant and short irrespective of a collision speed (orthe movement speed of the lock plate).

As a result, it is possible to suppress variations in characteristics ofenergy absorption at the time of the vehicle collision.

The tooth retreated from the lock plate may not overlap a second-closestpartition portion of the partition portions, which is second closest tothe steering member, when the tooth is viewed from the axial direction.

According to the above configuration, the tooth retreated from the lockplate does not overlap the second-closest partition portion secondclosest to the steering member, i.e., the highest partition portionamong partition portions serving as boundary portions between twoadjacent holes, when the tooth is viewed from the axial direction.Accordingly, when the steering shaft and the column jacket are caused toextend or contract in the state in which the tooth has retreated, thetooth does not interfere with any of the boundary portions, and hence itis possible to smoothly adjust the position of the steering member.

The tooth retreated from the lock plate may overlap a closest partitionportion of the partition portions, which is closest to the steeringmember, when the tooth is viewed from the axial direction.

According to the above configuration, the tooth having retreated fromthe lock plate overlaps the closest partition portion closest to thesteering member when the tooth is viewed from the axial direction.Accordingly, when the steering shaft and the column jacket are caused toextend or contract in the state in which the tooth has retreated, theclosest partition portion functions as a stopper, and can limit theextension/contraction amount of the steering shaft and the column jacketto a predetermined amount by coming in contact with the tooth.

The steering device may further include a biasing member that biases thetooth toward the lock plate.

According to the above configuration, since the biasing member biasesthe tooth toward the lock plate, even when the tooth is in pressurecontact with any partition portion, it is possible to cause the tooth tobe engaged with the next hole more reliably with the biasing force ofthe biasing member at the time of the vehicle collision.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the invention will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is a schematic perspective view of a steering device 1 accordingto an embodiment of the invention;

FIG. 2 is a schematic side view showing the schematic configuration ofthe steering device 1;

FIG. 3 is a schematic cross-sectional view of the steering device 1taken along the line of FIG. 2;

FIG. 4 is an exploded perspective view of the principal portion of thesteering device 1;

FIG. 5 is a schematic cross-sectional view of the steering device 1taken along the line V-V of FIG. 2;

FIG. 6 is a schematic sectional view of the steering device 1 taken longthe line VI-VI of FIG. 5;

FIG. 7 is a view showing a state in which a tooth 51 retreats from ahole 57 in the steering device 1 shown in FIG. 6;

FIG. 8 is a schematic diagram showing the tooth 51 in a half-lockedstate and its periphery.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinbelow, an embodiment of the invention will be described in detailwith reference to the accompanying drawings.

FIG. 1 is a schematic perspective view of a steering device 1 accordingto an embodiment of the invention. FIG. 2 is a schematic side viewshowing the schematic configuration of the steering device 1.

In FIG. 2, the left side on the paper sheet corresponds to the frontside of a vehicle body 2 to which the steering device 1 is mounted, theright side on the paper sheet corresponds to the rear side of thevehicle body 2, the upper side on the paper sheet corresponds to theupper side of the vehicle body 2, and the lower side on the paper sheetcorresponds to the lower side of the vehicle body 2.

With reference to FIG. 2, the steering device 1 mainly includes asteering shaft 3, a column jacket 4, a lower bracket 5, an upper bracket6 as a support bracket, and a lock mechanism 7.

In the steering shaft 3, a steering member 8 is mounted to a first end3A on the rear side, and a second end 3B on the front side is coupled toa steering mechanism 13 via a universal joint 9, an intermediate shaft10, a universal joint 11, and a pinion shaft 12. The steering mechanism13 is constituted by a rack and pinion mechanism and the like. Thesteering mechanism 13 steers a turning wheel such as a tire that is notshown in response to transmission of rotation of the steering shaft 3.

The steering shaft 3 has a substantially cylindrical or columnar shapethat extends in a front-rear direction of the vehicle body 2 as a whole.

In the following description, the direction in which the steering shaft3 extends is assumed to be an axial direction X. The axial direction Xin the embodiment is inclined relative to a horizontal direction suchthat the second end 3B is lower than the first end 3A. The rear side asthe first end side (the side where the steering member 8 is positioned)in the axial direction X is designated by a reference numeral “X1”,while the front side as the second side (the side opposite to the sidewhere the steering member 8 is positioned) in the axial direction X isdesignated by a reference numeral “X2”. The rear side X1 corresponds tothe rear side of the vehicle body 2, and the front side X2 correspondsto the front side of the vehicle body 2.

Among directions orthogonal to the axial direction X, a directionperpendicular to the paper sheet in FIG. 2 is referred to as aright-left direction Y, and a direction extending substantiallyvertically in FIG. 2 is referred to as an up-down direction Z. In theright-left direction Y, the far side on the paper sheet in FIG. 2 is aright side Y1, and the near side on the paper sheet is a left side Y2.The upper side in the up-down direction Z is designated by a referencenumeral “Z1”, and the lower side in the up-down direction Z isdesignated by a reference numeral “Z2”.

Note that, in each of the drawings other than FIG. 2, directionscorresponding to the directions X to Z in FIG. 2 are designated by thesame reference numerals as those in FIG. 2.

The steering shaft 3 includes a cylindrical or columnar upper shaft 14and a cylindrical or columnar lower shaft 15. The upper shaft 14 isdisposed on the rear side X1 of the lower shaft 15. The upper shaft 14and the lower shaft 15 are concentrically arranged.

An end portion of the upper shaft 14 on the rear side X1 corresponds tothe first end 3A of the steering shaft 3, and the steering member 8 iscoupled to the end portion of the upper shaft 14 on the rear side X1. Inthe upper shaft 14, at least an end portion on the front side X2 isformed in a cylindrical shape. Into the end portion of the upper shaft14 on the front side X2, an end portion of the lower shaft 15 on therear side X1 is inserted from the front side X2.

The upper shaft 14 and the lower shaft 15 are fitted to each other byspline fitting or serration fitting. Accordingly, the upper shaft 14 andthe lower shaft 15 can rotate together integrally, and can move relativeto each other along the axial direction X. Therefore, the steering shaft3 is telescopically adjustable (the steering shaft 3 can extend orcontract) in the axial direction X.

The column jacket 4 is a hollow body that extends in the axial directionX as a whole. The steering shaft 3 is accommodated in the column jacket4. The column jacket 4 has a substantially tubular upper jacket 16 and asubstantially tubular lower jacket 17 that extend in the axial directionX.

The upper jacket 16 is positioned on the rear side X1 of the lowerjacket 17. In other words, the lower jacket 17 is positioned on thefront side X2 of the upper jacket 16. The lower jacket 17 is thickerthan the upper jacket 16, and is fitted on the upper jacket 16.Specifically, an end portion 16A of the upper jacket 16 on the frontside X2 is inserted into an end portion 17A of the lower jacket 17 onthe rear side X1 from the rear side X1. In this state, the upper jacket16 can move relative to the lower jacket 17 in the axial direction X.With this relative movement, the column jacket 4 is telescopicallyadjustable in the axial direction X.

The steering shaft 3 is coupled to the column jacket 4 via a bearingthat is not shown, and hence the column jacket 4 rotatably supports thesteering shaft 3.

Specifically, the upper shaft 14 and the upper jacket 16 are coupled toeach other via a bearing that is not shown. In addition, the lower shaft15 and the lower jacket 17 are coupled to each other via a bearing thatis not shown. Accordingly, the coupled body of the upper shaft 14 andthe upper jacket 16 can move relative to the lower shaft 15 and thelower jacket 17 in the axial direction X. With this, the column jacket 4is telescopically adjustable together with the steering shaft 3.

The positional adjustment of the steering member 8 in the axialdirection X by extension or contraction of the steering shaft 3 and thecolumn jacket 4 is called a telescopic adjustment.

The lower bracket 5 supports the portion of the column jacket 4 on thefront side X2, and couples the steering device 1 to the vehicle body 2.Specifically, the lower bracket 5 supports the portion of the lowerjacket 17 on the front side X2.

The lower bracket 5 includes a movable bracket 18 fixed to the lowerjacket 17, a fixed bracket 19 fixed to the vehicle body 2, and a centralshaft 20 extending in the right-left direction Y.

A pair of the right and left movable brackets 18 are provided on, e.g.,an upper outer peripheral surface of an end portion 17B of the lowerjacket 17 on the front side X2 (see FIG. 1). The movable bracket 18 istiltably supported by the fixed bracket 19 via the central shaft 20. Asa result, the entire column jacket 4 can tilt vertically about thecentral shaft 20 together with the steering shaft 3. An orientationadjustment of the steering member 8 by the tilt is called a tiltadjustment. The lower jacket 17 is coupled to the fixed bracket 19 fixedto the vehicle body 2 via the central shaft 20, and hence the lowerjacket 17 can tilt but cannot move in the axial direction X.

The upper bracket 6 supports the portion of the column jacket 4 on therear side X1 of the movable bracket 18. Specifically, the upper bracket6 supports the portion of the lower jacket 17 on the rear side X1.

FIG. 3 is a schematic cross-sectional view of the steering device 1taken along the line III-III of FIG. 2.

With reference to FIG. 3, the upper bracket 6 has a groove shape that isopened downward, and is formed to be bilaterally symmetric with respectto the column jacket 4 so as to have a substantially U-shape that isvertically inverted when viewed from the axial direction X.Specifically, the upper bracket 6 integrally includes a pair of sideplates 21 that oppose each other with the column jacket 4 interposedtherebetween and a coupling plate 22 that is coupled to the upper endportions of the pair of the side plates 21. The side plate 21 is thin inthe right-left direction Y, and the coupling plate 22 is thin in theup-down direction Z.

In the pair of the side plates 21, tilt elongated holes 23 are formed atthe same positions when viewed from the right-left direction Y. The tiltelongated hole 23 extends in the up-down direction Z or, to be precise,in a tilt direction as a circumferential direction with the centralshaft 20 (see FIG. 2) serving as the center. The coupling plate 22 hasextending portions that extend outward in the right-left direction Ybeyond the pair of the side plates 21, and the entire upper bracket 6 isfixed to the vehicle body 2 using bolts (not shown) or the like that areinserted into the extending portions.

Herein, in a portion on the lower side Z2 in the end portion 17A of thelower jacket 17 on the rear side X1, a slit 24 as a cut-out that extendsin the axial direction X is formed (see also FIG. 1). The slit 24 isopened to both of the rear side X1 and the lower side Z2 from the endportion 17A toward the outside of the lower jacket 17 (see also FIG. 1).Accordingly, the end portion 17A of the lower jacket 17 has a verticallyinverted substantially U-shaped cross section.

In addition, at the end portion 17A of the lower jacket 17, a pair ofsupport portions 25 that extend to the lower side Z2 while defining theslit 24 in the right and left direction Y is integrally provided. Eachsupport portion 25 has a substantially rectangular solid shape thatspreads in the axial direction X and the up-down direction Z.

In the pair of the support portions 25, through holes 26 that passthrough the support portions 25 in the right-left direction Y are formedat the same positions when viewed from the right-left direction Y.

The steering device 1 includes a clamping shaft 27 that is inserted intoa portion where the through hole 26 and the tilt elongated hole 23overlap each other when viewed from the right-left direction Y. Theclamping shaft 27 has a substantially columnar shape that extends in theright-left direction Y. Both ends of the clamping shaft 27 in theright-left direction Y protrude outward in the right-left direction Yfrom the pair of the side plates 21 of the upper bracket 6. At the endportion of the clamping shaft 27 on the left side Y2, a head portion 29having a diameter larger than that of the clamping shaft 27 is formed.

In the steering device 1, between the head portion 29 and the side plate21 on the left side Y2, a grippable lever-type operation member 30 thatis operated for the telescopic adjustment and the tilt adjustment, anannular cam 31, and a cam follower 32 are arranged in this order fromthe left side Y2.

The clamping shaft 27 is inserted into a base end portion 30A of theoperation member 30 on one end side in a longitudinal direction, the cam31, and the cam follower 32. Since the clamping shaft 27 is insertedinto each tilt elongated hole 23 of the upper bracket 6, the operationmember 30, the cam 31, and the cam follower 32 are supported by theupper bracket 6 via the clamping shaft 27.

The operation member 30 and the cam 31 can rotate integrally with eachother relative to the clamping shaft 27, while the cam follower 32 canrotate relative to the clamping shaft 27 and can move in the right-leftdirection Y. However, a portion of the cam follower 32 that is insertedinto the tilt elongated hole 23 of the side plate 21 on the left side Y2is formed with two opposing surfaces, and hence the slipping of the camfollower 32 is prevented by the tilt elongated hole 23.

To the end portion of the clamping shaft 27 on the right side Y1, a nut33 is attached. Between the nut 33 and the side plate 21 on the rightside, an interposed member 34, a needle roller bearing 35, and a thrustwasher 36 are arranged in this order from the left side Y2. The clampingshaft 27 is inserted into the interposed member 34, the needle rollerbearing 35, and the thrust washer 36.

The clamping shaft 27 can move in the above-described tilt direction ineach tilt elongated hole 23 of the upper bracket 6. When a use such as adriver moves the steering member 8 in the up-down direction Z for thetilt adjustment, the entire column jacket 4 tilts relative to the upperbracket 6 as described above. The tilt adjustment of the steering member8 is performed within a range in which the clamping shaft 27 can move inthe tilt elongated hole 23.

When a user grips a tip portion 30B of the operation member 30 on oneend side in the longitudinal direction and rotates the operation member30 about the clamping shaft 27 in a first direction after the userperforms the telescopic adjustment or the tilt adjustment, the cam 31rotates, and cam protrusions 37 formed on the cam 31 and the camfollower 32 get on each other. With this, the cam follower 32 moves tothe right side Y1 along the axial direction of the clamping shaft 27,and is pushed against the side plate 21 on the left side Y2. By thepushing, the pair of the side plates 21 are clamped from both sides inthe right-left direction Y between the cam follower 32 and theinterposed member 34.

With this, the pair of the side plates 21 holds the support portions 25of the lower jacket 17 between them from both sides in the right-leftdirection Y, and a frictional force is thereby generated between eachside plate 21 and the support portion 25. With the frictional force, theposition of the column jacket 4 is locked, and the steering member 8 islocked at the position after the tilt adjustment and is prevented frommoving in the tilt direction.

In addition, the pair of the support portions 25 of the lower jacket 17is held between the side plates 21, and the distance between the pair ofthe support portions 25 is reduced so that the inner portion of thelower jacket 17 is narrowed, and the lower jacket 17 comes in pressurecontact with the upper jacket 16 in the lower jacket 17.

With this, the frictional force is generated between the upper jacket 16and the lower jacket 17, and the position of the upper jacket 16 isthereby locked, and the steering member 8 is thereby locked at theposition after the telescopic adjustment and prevented from moving inthe axial direction X.

Thus, the state of the steering device 1 when the position of thesteering member 8 is fixed in each of the tilt direction and the axialdirection X is called a “locked state”.

In the steering device 1 in the locked state, when the operation member30 is rotated in a second direction opposite to the first direction, thecam 31 rotates relative to the cam follower 32, and the cam follower 32moves to the left side Y2 along the axial direction of the clampingshaft 27. Then clamping to the pair of the side plates 21 between thecam follower 32 and the interposed member 34 is released. As a result,the frictional force between each side plate 21 and the support portion25 and the frictional force between the lower jacket 17 and the upperjacket 16 disappear, and hence the steering member 8 becomes capable ofmoving in the axial direction X and the tilt direction. With this, itbecomes possible to perform the telescopic adjustment and the tiltadjustment of the steering member 8 again.

Thus, the state of the steering device 1 when the fixing of the positionof the steering member 8 in the tilt direction and the axial direction Xis released is called a “lock-released state”.

Next, the lock mechanism 7 will be described in detail. The lockmechanism 7 is a mechanism for firmly locking the upper jacket 16 suchthat the upper jacket 16 does not move in the axial direction X in thesteering device 1 in the locked state, and is provided in the vicinityof the central portion of the clamping shaft 27 in the right-leftdirection Y.

FIG. 4 is an exploded perspective view of the principal portion of thesteering device 1. In FIG. 4, for the convenience of description, theupper jacket 16 is represented by using a two-dot chain line. FIG. 5 isa schematic cross-sectional view of the steering device 1 taken alongthe line V-V of FIG. 2. FIG. 6 is a schematic cross-sectional view ofthe steering device 1 taken long the line VI-VI of FIG. 5. In FIG. 6,for the convenience of description, the depiction of the steering shaft3 is omitted (the same applies to FIG. 7 described later).

With reference to FIG. 4, the lock mechanism 7 includes a cam 38 as atransmission member, a support shaft 39, a lock member 40, a biasingmember 41, and a lock plate 42.

The cam 38 integrally includes a cylindrical boss portion 38A thatextends in the right-left direction Y, and a cam portion 38B thatprotrudes outward in the radial direction of the boss portion 38A fromone position on the periphery of the boss portion 38A. The cam portion38B has a substantially triangular shape that is tapered with approachto the outside in the radial direction of the boss portion 38A whenviewed from the right-left direction Y.

The outer tip portion of the cam portion 38B in the radial direction isdesignated by a reference numeral “38C”. The cam portion 38B has a pairof arc-shaped surfaces 38D that connect the tip portion 38C and theouter peripheral surface of the boss portion 38A and are smoothlycoupled to each other on the outer peripheral surface of the bossportion 38A.

The cam 38 is disposed in the slit 24 of the lower jacket 17, and theportion of the clamping shaft 27 exposed in the slit 24 between the pairof the support portions 25 is inserted into the boss portion 38A (seealso FIG. 3). The boss portion 38A and the clamping shaft 27 are fittedto each other by spline fitting or the like. Accordingly, the cam 38 canrotate integrally with the clamping shaft 27 in accordance with theoperation of the operation member 30.

The support shaft 39 is a substantially columnar shape that extends inthe right-left direction Y. With regard to the support shaft 39, withreference to FIG. 5, one through hole 43 that passes through the supportportion 25 in the right-left direction Y is formed at the position onthe front side X2 of the through hole 26 in each support portion 25 ofthe lower jacket 17. In each support portion 25, the through hole 43 hasan increased diameter portion 44 of which the diameter is increased onthe outside in the right-left direction Y. The support shaft 39 isinserted into the through hole 43 of each support portion 25, and canrotate in a circumferential direction C of the support shaft 39 (seeFIG. 4).

Both end portions of the support shaft 39 in the right-left direction Yreach the increased diameter portions 44. A push nut 45 is attached toone of the end portions of the support shaft 39 in the right-leftdirection Y. In the embodiment, the push nut 45 is attached to the endportion of the support shaft 39 on the left side Y2. The support shaft39 is positioned in the right-left direction Y by the push nut 45.

Returning to FIG. 4, the lock member 40 has a substantially V-shape thatis inclined by about 90° to the rear side X1 when viewed from theright-left direction Y. The lock member 40 includes a base end portion46, and a lock portion 47 and a contact portion 48 that extend from thebase end portion 46 to the rear side X1.

The base end portion 46 is a coupling portion of the lock portion 47 andthe contact portion 48. The base end portion 46 is formed with aninsertion hole 49 that passes through the base end portion 46 in theright-left direction Y. On each of both side surfaces of the base endportion 46 in the right-left direction Y, a cylindrical portion 50 thatprotrudes outward in the right-left direction Y while surrounding theinsertion hole 49 is formed. The cylindrical portion 50 is considered tobe a part of the base end portion 46.

The lock portion 47 has a shape that extends from the base end portion46 to the rear side X1 and the upper side Z1. The end portion of thelock portion 47 on the rear side X1 serves as a tooth 51, and the tooth51 is bent toward the upper side Z1. In addition, a notch 52 thatextends in the right-left direction Y is formed in a lower surface 47Aof the lock portion 47. The notch 52 is adjacent to the front side X2 ofthe tooth 51.

The notch 52 is a groove that extends in the right-left direction Y. Theportion of the lock portion 47 in which the notch 52 is formed is calleda low-strength portion 53. The thickness of the lock portion 47 islocally reduced in the low-strength portion 53, and hence the strengthin the low-strength portion 53 is lowered locally.

The contact portion 48 has a shape that extends from the base endportion 46 to the rear side X1. The contact portion 48 is positioned onthe lower side Z2 of the lock portion 47.

The above-described lock member 40 is disposed on the front side X2 ofthe cam 38 in the slit 24 of the lower jacket 17 (see also FIG. 6). Theportion of the support shaft 39 described above positioned in the slit24 is inserted into the insertion hole 49 of the base end portion 46 ofthe lock member 40. The support shaft 39 and the base end portion 46 arefitted to each other by spline fitting or the like. Accordingly, thelock member 40 can rotate in the circumferential direction C about theshaft of the support shaft 39 together with the support shaft 39.

Moreover, since the support shaft 39 is inserted into the through hole43 of each support portion 25 of the lower jacket 17 (see FIG. 5), thelock member 40 is supported by the lower jacket 17 via the support shaft39.

In addition, the above-described cam 38 is disposed between the lockportion 47 and the contact portion 48 of the lock member 40, and the camportion 38B of the cam 38 comes in contact with an upper surface 48A ofthe contact portion 48 from the upper side Z1 (see FIG. 6).

The biasing member 41 is a spring formed by bending a wire or the like.The biasing member 41 integrally includes a coil-shaped portion 54 thatis wound around the outer peripheral surface of the cylindrical portion50 of the base end portion 46 on the left side Y2 from the outside, anda holding portion 55 and a deformed portion 56 that extend from thecoil-shaped portion 54 to the rear side X1. The deformed portion 56 isdisposed on the lower side Z2 of the holding portion 55. An end portion56A of the deformed portion 56 on the rear side X1 is bent to the rightside Y1.

In the biasing member 41, the holding portion 55 engages the outerperipheral surface of the portion of the boss portion 38A of the cam 38on the left side Y2 of the cam portion 38B from the upper side Z1, andthe end portion 56A of the deformed portion 56 engages the contactportion 48 of the lock member 40 from the lower side Z2 (see FIG. 6). Inthe biasing member 41, a force that moves the deformed portion 56 towardthe holding portion 55 to the upper side Z1 is constantly generated, andthis force serves as a biasing force for biasing the entire lock member40 to the upper side Z1 along the circumferential direction C.

The lock plate 42 has a plate shape that is long in the axial directionX and is thick in the up-down direction Z, and is curved along an outerperipheral surface 16B of the upper jacket 16.

The lock plate 42 is disposed at the portion of the underside of theouter peripheral surface 16B of the upper jacket 16 that is exposed tothe slit 24 of the lower jacket 17 (see FIGS. 3 and 5). The lock plate42 is fixed to the upper jacket 16 by welding or the like. Accordingly,the lock plate 42 can move relative to the lower jacket 17 in the axialdirection X together with the upper jacket 16.

The lock plate 42 is positioned on the upper side Z1 of (immediatelyabove) the lock member 40. Accordingly, the lock member 40 (the tooth51) that is biased to the upper side Z1 by the biasing member 41 isbiased toward the lock plate 42.

In the lock plate 42, a plurality of holes 57 that extend along thecircumferential direction of the outer peripheral surface 16B of theupper jacket 16 are formed so as to be arranged in the axial directionX. The number of holes 57 is nine in the embodiment, but the numberthereof is not limited thereto. Each hole 57 passes through the lockplate 42 in the up-down direction Z as the direction of thickness of thelock plate 42. Partition portions 58 are provided in the lock plate 42so as to correspond to the plurality of the holes 57 on a one-to-onebasis. The partition portion 58 is adjacent to the rear side X1 of thehole 57. Accordingly, the number of provided partition portions 58 isequal to the number of holes 57, and a plurality of the partitionportions 58 are arranged in the axial direction X. The partition portion58 other than the rearmost partition portion 58 closest to the steeringmember 8 forms a boundary portion between two holes 57 adjacent to eachother in the axial direction X.

In the above-described locked state shown in FIG. 6, the cam portion 38Bof the cam 38 is directed to the front side X2, and the arc-shapedsurface 38D of the cam portion 38B on the lower side Z2 comes in surfacecontact with the upper surface 48A of the contact portion 48 of the lockmember 40 from the upper side Z1.

In the locked state, the tooth 51 of the lock portion 47 in the lockmember 40 is normally fitted in and engaged with any of the holes 57 inthe lock plate 42 in a state in which the tooth 51 has entered the hole57 of the lock plate 42 from the lower side Z2. The positions of thelock member 40 and the tooth 51 when the tooth 51 has entered the hole57 of the lock plate 42 are called “advance positions”.

The biasing member 41 biases the entire lock member 40 to the upper sideZ1, as described above. With this, the tooth 51 is kept engaged with thehole 57 of the lock plate 42. That is, in the locked state, the tooth 51is biased so as to be constantly positioned at the advance position.

In the state in which the tooth 51 is at the advance position and isengaged with any hole 57 in the lock plate 42 in the locked state, thetooth 51 engaged with the hole 57 is sandwiched between the partitionportions 58 on both sides in the axial direction X. Accordingly, themovement of the lock plate 42 in the axial direction X is prevented bythe lock member 40. In this connection, in the case where the tooth 51is engaged with the frontmost hole 57, the tooth 51 is sandwichedbetween the frontmost partition portion 58 and a front end portion 42Bof the lock plate 42 that defines the hole 57 from the front side X2.

In addition, as described above, the lock plate 42 is fixed to the upperjacket 16, and the lock member 40 is fixed to the lower jacket 17 viathe support shaft 39. Accordingly, when the tooth 51 is at the advanceposition in the locked state, the movement of the upper jacket 16relative to the lower jacket 17 in the axial direction X is prevented.

With this, in addition to the frictional force between the lower jacket17 and the upper jacket 16, the tooth 51 fixed to the side of the lowerjacket 17 is engaged with the hole 57 of the lock plate 42 fixed to theupper jacket 16, and it is thereby possible to firmly lock the positionof the upper jacket 16 in the axial direction X. Accordingly, theextension and contraction of the steering shaft 3 and the column jacket4 are stopped and the position of the steering member 8 in the axialdirection X is locked, and hence the telescopic adjustment is preventedfrom being performed.

As shown in FIG. 6, in the case where the steering device 1 is in thelocked state and the tooth 51 is at the advance position, a vehiclehaving the steering device 1 and the vehicle body 2 can perform normalrunning.

At the time of a vehicle collision, a collision load from the rear sideX1 caused by what is called a secondary collision acts on the steeringshaft 3 and the column jacket 4. At this point, the upper jacket 16 andthe upper shaft 14 starts to contract, whereby the load acts on thetooth 51 of the lock member 40 engaged with the hole 57 of the lockplate 42 from the rear side X1. With this, the lock portion 47 of thelock member 40 is broken at the low-strength portion 53.

With this, the tooth 51 engaged with the hole 57 of the lock plate 42 inthe lock portion 47 is separated from the portion other than the tooth51 in the lock portion 47 at the low-strength portion 53. As a result,the upper jacket 16 fixed to the lock plate 42 moves relative to thelower jacket 17 fixed to the lower bracket 5 so as to contract. Withthis relative movement, it is possible to absorb energy at the time ofthe vehicle collision (at the time of the secondary collision).

FIG. 7 is a view showing a state in which the tooth 51 has retreatedfrom the hole 57 in the steering device 1 shown in FIG. 6.

In the state in FIG. 6, the clamping shaft 27 is rotated by operatingthe operation member 30 such that the steering device 1 is switched fromthe locked state to the lock-released state. Then the cam 38 rotatesintegrally with the clamping shaft 27 counterclockwise when viewed fromthe left side Y2 such that the cam portion 38B that has been directed tothe front side X2 is directed to the lower side Z2. With the rotation ofthe cam 38, the cam portion 38B pushes down the contact portion 48 ofthe lock member 40 to the lower side Z2.

With this, the entire lock member 40 rotates about the support shaft 39to the lower side Z2 against the biasing force of the biasing member 41.With this, the tooth 51 of the lock member 40 starts to retreat from thelock plate 42 to the lower side Z2, and be disengaged from the hole 57of the lock plate 42 with which the tooth 51 has been engaged and.

As shown in FIG. 7, when the steering device 1 is brought into thelock-released state, the cam portion 38B is directed to the lower sideZ2, and the lock member 40 is fully rotated to the lower side Z2. Atthis point, the tooth 51 of the lock member 40 completely retreats fromthe lock plate 42 to the lower side Z2, and is completely disengagedfrom the hole 57 of the lock plate 42 with which the tooth 51 has beenengaged. The position of the tooth 51 that have retreated from the lockplate 42 in this way are called “retreat positions”.

Similarly to the locked state, in the lock-released state as well, thebiasing member 41 biases the entire lock member 40 to the upper side Z1.In addition, the cam portion 38B of the cam 38 comes in contact with thecontact portion 48 of the lock member 40 from the upper side Z1.Accordingly, the tooth 51 of the lock member 40 is constantly biasedtoward the advance position (toward the lock plate 42) by the biasingmember 41, but the tooth 51 is positioned at the retreat position in thelock-released state.

In the state in which the tooth 51 is at the retreat position, theprevention of the movement of the lock plate 42 in the axial direction Xby the lock member 40 is released. As a result, the upper jacket 16 canfreely move relative to the lower jacket 17 in the axial direction Xwith the lock plate 42, and hence it becomes possible to cause thesteering shaft 3 and the column jacket 4 to extend or contract tothereby perform the telescopic adjustment of the steering member 8. Whenthe telescopic adjustment is performed, the individual holes 57 of thelock plate 42 sequentially pass on the upper side Z1 of the tooth 51 atthe retreat position along the axial direction X. In addition, in thisstate, it is also possible to perform the tilt adjustment.

Herein, in the lower jacket 17, in an upper wall 59 positioned on theside opposite to the side of the support portion 25 with the upperjacket 16 interposed therebetween in the up-down direction Z, anelongated hole 60 that extends in the axial direction X is formed.

The elongated hole 60 passes through the upper wall 59 of the lowerjacket 17 in the up-down direction Z. Both end portions of the elongatedhole 60 in the axial direction X are closed, and are not opened to theoutside of the lower jacket 17.

Into the elongated hole 60, an engagement portion 61 is looselyinserted. The engagement portion 61 has a substantially rectangularsolid shape. In the engagement portion 61, an engagement convex portion62 provided on the surface on the lower side Z2 is fitted by, forexample, press-fitting in an engagement concave portion 63 provided onthe outer peripheral surface 16B of the upper jacket 16 such that theengagement convex portion 62 is not allowed to be detached from theengagement concave portion 63. With this, the engagement portion 61 isfixed to the upper jacket 16. The engagement portion 61 may also befixed to the upper jacket 16 by welding or screw fastening.

The upper jacket 16 can move relative to the lower jacket 17 within arange in which the engagement portion 61 can move in the elongated hole60. A length L (see FIG. 1) of the elongated hole 60 in the axialdirection X corresponds to the sum of the maximum movement amount of theupper jacket 16 in the telescopic adjustment of the steering member 8and the maximum movement amount of the upper jacket 16 for the energyabsorption at the time of the vehicle collision.

After the telescopic adjustment or the tilt adjustment of the steeringmember 8, as shown in FIG. 6, the operation member 30 is operated again,and the steering device 1 is brought into the locked state and the tooth51 is moved to the locked position, whereby the position of the upperjacket 16 is locked in the axial direction X or tilt direction Thus, thetooth 51 can be advance to or retreat from the lock plate 42 inaccordance with the operation of the operation member 30, and is engagedwith any of the holes 57 in the lock plate 42 in the state in which thetooth 51 advances to the lock plate 42 at the advance position.

Next, the lock plate 42 will be described in detail.

With reference to FIG. 7, in each partition portion 58 of the lock plate42, a direction toward the tooth 57 at the retreat position along adepth direction (the up-down direction Z) of the hole 57 corresponds tothe lower side Z2. Herein, the height of each partition portion 58 in adirection toward the lower side Z2 is defined as a height H. The heightH of the partition portion 58 corresponds to the dimension of thepartition portion 58 in the up-down direction Z, or the length of thepartition portion 58 from the upper surface (the surface fixed to theupper jacket 16) of the rock plate 42 to an end of the partition portion58 on the lower side Z2 (the side toward the tooth 51 at the retreatposition). The partition portions 58 are provided such that the height Hof a rear-side partition portion 58 is greater than that of a front-sidepartition portion 58 positioned on the front side X2 (i.e., the secondend side) of the rear-side partition portion 58. That is, the rear-sidepartition portion 58 protrudes closer to the tooth 51 than thefront-side partition portion 58. As a result, the height of the entirepartition portions 58 increases stepwise toward the rear side X1, withapproach to the steering member 8. The direction toward the steeringmember 8 is a direction opposite to the movement direction (the frontside X2) of the lock plate 42 at the time of the vehicle collision.

A surface that defines the hole 57 in each partition portion 58 is aflat surface 58B that extends in the up-down direction Z.

A distance D in the axial direction X between the front end edge of thefrontmost hole 57 and the rear end edge of the rearmost hole 57 issubstantially equal to the maximum movement amount of the upper jacket16 in the telescopic adjustment of the steering member 8.

As shown in FIG. 7, the tooth 51 at the retreat position is positionedon the lower side Z2 of a partition portion 58C (the second partitionportion from the rear side X1) that is second closest to the steeringmember 8 (that is, the tooth 51 does not overlap the lower end portionof the partition portion 58C) when viewed from the axial direction X.Accordingly, when the steering shaft 3 and the column jacket 4 aretelescopically adjusted in the state in which the tooth 51 hasretreated, the tooth 51 does not interfere with any of the partitionportions 58 other than the rearmost partition portion 58A that isclosest to the steering member 8, and hence it is possible to smoothlyperform the telescopic adjustment of the position of the steering member8. In addition, the tooth 51 at the retreat position may overlap thelower end portion of the rearmost partition portion 58A closest to thesteering member 8 or may also be positioned below the lower end portionof the partition portion 58A when viewed from the axial direction X. Inthe case where the tooth 51 at the retreat position overlaps the lowerend portion of the rearmost partition portion 58A, the rearmostpartition portion 58A serves as a stopper. That is, in the telescopicadjustment, the rearmost partition portion 58A comes in contact with thetooth 51, whereby it is possible to prevent the movement of the tooth 51to the rear side X1 of the rearmost hole 57 and limit theextension/contraction amount (to be precise, the contraction amount) ofthe steering shaft 3 and the column jacket 4 to a predetermined amount.

When the tooth 51 at the retreat position is caused to move to theadvance position by operating the operation member 30 after thetelescopic adjustment or the tilt adjustment, in most cases, the tooth51 is fitted in any hole 57 without hitting against the partitionportion 58 of the lock plate 42.

However, depending on the position of the tooth 51 in the axialdirection X when the operation member 30 is operated, as shown in FIG. 8there are cases where the tooth 51 hits against the partition portion 58from the lower side Z2 and is brought into pressure contact with thepartition portion 58 before the tooth 51 reaches the advance position.

When the vehicle collision occurs in a half-locked state in which thetooth 51 is not engaged with any hole 57 and comes in pressure contactwith any partition portion 58 from the lower side Z2, the lock plate 42moves to the front side X2 together with the upper jacket 16 before thelock portion 47 of the lock member 40 is broken at the low-strengthportion 53 (before the separation). With the movement of the lock plate42, the position of the hole 57 (referred to as the “next hole 57”)adjacent to the rear side X1 of the partition portion 58 with which thetooth 51 has been in pressure contact (referred to as the“pressure-contacted partition portion 58”) matches the position of thetooth 51, and the tooth 51 is fitted in the next hole 57. Thereafter,the lock portion 47 is broken at the low-strength portion 53, wherebythe separation occurs. However, depending on a collision speed (in otherwords, the movement speed of the lock plate 42), there is a possibilitythat the lock plate 43 moves in the axial direction X before the tooth51 is fitted in the next hole 57.

Unlike the invention in the application, when the height H of thepartition portion 58 is constant, there is a possibility that, withoutbeing fitted in the next hole 57, the tooth 51 gets over the subsequentpartition portion 58 and significantly moves without being fitted in ahole 57. As a result, variations occur in characteristics of energyabsorption (separation characteristics) at the time of the vehiclecollision in accordance with the movement distance of the tooth 51before the tooth 51 is fitted in a hole 57.

However, in the invention, the height of the partition portion 58increases stepwise with approach to the steering member 8. Accordingly,irrespective of the collision speed, with the movement of the lock plate42, the tooth 51 in the half-locked state comes in contact with the flatsurface 58B on the front side X2 of another partition portion 58(referred to as the “next partition portion 58”) that is higher than thepressure-contacted partition portion 58 and is adjacent to the rear sideX1 of the pressure-contacted partition portion 58. With this, the tooth51 is guided to the hole 57 between the pressure-contacted partitionportion 58 and the next partition portion 58 by the next partitionportion 58, and can be engaged with the hole 57 between thepressure-contacted partition portion 58 and the next partition portion58. That is, even when the vehicle collision has occurred in the statein which the tooth 51 is in pressure contact with any partition portion58, it is possible to reliably cause the tooth 51 to be engaged with thenext hole 57 adjacent to the rear side X1 of the pressure-contactedpartition portion 58. With this, it is possible to make the movementdistance of the tooth 51 from when the tooth 51 is in pressure contactwith the partition portion 58 to when the tooth 51 is engaged with thenext hole 57 constant and short irrespective of the collision speed.

As a result, it is possible to suppress variations in characteristics ofenergy absorption at the time of the vehicle collision.

Further, since the biasing member 41 biases the tooth 51 toward the lockplate 42, even when the tooth 51 is in pressure contact with anypartition portion 58, it is possible to cause the tooth 51 to be engagedwith the next hole 57 more reliably with the biasing force of thebiasing member 41 at the time of the vehicle collision.

In addition, even when the vehicle collision occurs in the half-lockedstate, the tooth 51 is fitted in the next hole 57 more reliably, andhence it is not necessary to finely set the biasing force of the biasingmember 41 in consideration of the collision speed and the weight of thetooth 51.

The invention is not limited to the embodiments described above, andvarious changes can be made within the scope of the claims.

For example, in the embodiment described above, the tooth 51 isconstantly biased so as to advance toward the lock plate 42 by thebiasing member 41, and retreats by receiving the force of the cam 38that rotates by the operation of the operation member 30. That is, thetooth 51 and the clamping shaft 27 of the operation member 30 aredifferent components that are independent of each other, and are linkedwith each other via the cam 38. Instead of this configuration, the tooth51 may be integrated with the clamping shaft 27, and the tooth 51 may becaused to advance or retreat in response to the operation of theoperation member 30 without the intervention of the cam 38.

In addition, the invention can also be applied to the steering devicecapable of only the telescopic adjustment.

What is claimed is:
 1. A steering device comprising: a steering shaftincluding a first end to which a steering member is mounted and a secondend, wherein the steering shaft is telescopically adjustable in an axialdirection of the steering shaft; a column jacket rotatably supportingthe steering shaft and including an upper jacket positioned on a firstend side and a lower jacket positioned on a second end side, wherein thecolumn jacket is telescopically adjustable together with the steeringshaft with movement of the upper jacket relative to the lower jacket inthe axial direction; a lock plate fixed to the upper jacket and providedwith a plurality of holes arranged in the axial direction and aplurality of partition portions arranged in the axial direction, whereineach of the partition portions is adjacent to the first end side of thecorresponding one of the holes; a support bracket fixed to a vehiclebody and supporting the column jacket; an operation member supported bythe support bracket, wherein the operation member is operated when thesteering shaft and the column jacket are telescopically adjusted; and atooth that advances to and retreats from the lock plate in accordancewith operation of the operation member, and that advances to the lockplate to be engaged with one of the holes of the lock plate, wherein thepartition portions are provided such that a height of a first end-sidepartition portion in a direction toward the tooth retreated from thelock plate is greater than that of a second end-side partition portionpositioned on the second end side of the first end-side partitionportion.
 2. The steering device according to claim 1, wherein the toothretreated from the lock plate does not overlap a second-closestpartition portion of the partition portions, which is second closest tothe steering member, when the tooth is viewed from the axial direction.3. The steering device according to claim 1, wherein the tooth retreatedfrom the lock plate overlaps a closest partition portion of thepartition portions, which is closest to the steering member, when thetooth is viewed from the axial direction.
 4. The steering deviceaccording to claim 1, further comprising a biasing member that biasesthe tooth toward the lock plate.